[1H] Magnetic Resonance Spectroscopy of Urine: Diagnosis of a Guanidinoacetate Methyl Transferase Deficiency Case

Abstract

For the first time, the use of urine [¹H] magnetic resonance spectroscopy has allowed the detection of 1 case of guanidinoacetate methyl transferase in a database sample of 1500 pediatric patients with a diagnosis of central nervous system impairment of unknown origin. The urine [¹H] magnetic resonance spectroscopy of a 9-year-old child, having severe epilepsy and nonprogressive mental and motor retardation with no apparent cause, revealed a possible guanidinoacetic acid increase. The definitive assignment of guanidinoacetic acid was checked by addition of pure substance to the urine sample and by measuring [¹H]-[¹H] correlation spectroscopy. Diagnosis of guanidinoacetate methyl transferase deficiency was further confirmed by liquid chromatography—mass spectrometry, brain [¹H] magnetic resonance spectroscopy, and mutational analysis of the guanidinoacetate methyl transferase gene. The replacement therapy was promptly started and, after 1 year, the child was seizure free. We conclude that for this case, urine [¹H] magnetic resonance spectroscopy screening was able to diagnose guanidinoacetate methyl transferase deficiency.

Keywords

guanidinoacetate methyl transferase deficiency guanidinoacetic acid urine [1H] magnetic resonance spectroscopy epilepsy

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